1. Field of the Invention
This invention relates to aqueous silicone emulsions which provide an elastomeric product upon removal of the water under ambient conditions.
2. Description of the Prior Art
A method of polymerizing organosiloxanes in an aqueous emulsion using a surface active sulfonic acid catalyst is described by Findlay et al. in U.S. Pat. No. 3,294,725, issued Dec. 27, 1966. They teach neutralization of the emulsion with a base to a pH of approximately 7 for maximum stability. They obtain emulsions of non-gelled fluid. They described tough rubbery films obtained by adding colloidal silica filler to their emulsion and breaking the mixed emulsion.
Johnson et al. in U.S. Pat. No. 4,221,688, issued Sept. 9, 1980, teach a silicone emulsion having a dispersed phase of an anionically stabilized hydroxylated polydiorganosiloxane, an organic tin compound, and a colloidal silica and a continuous phase of water in which the pH is 9.0 to 11.5. Upon removal of the water at ambient conditions, a crosslinked elastomeric product is formed. They teach that additional ingredients such as thickeners and fillers can be present to modify the properties of the emulsion or the elastomeric product. Colloidal clay is a suggested thickener. A wide variety of fillers are suggested for use as extending fillers, ultraviolet light screening agents, and pigments.
When the emulsion of Johnson et al. is extended with fillers, the resulting elastomeric product has many uses as a coating or caulking material.